This invention relates to a method and an apparatus for replenishing paint into a cartridge, suitable for use, for example, in replenishing paint cartridges of different colors which are adapted to be replaceably mounted on a coating system in the course of a coating operation.
Generally, rotary atomizing head type coating systems are widely resorted to in coating vehicle bodies or the like. In this regard, recently, coating systems of this sort are required to meet demands for reductions of the amounts of paint and solvent which have be discarded at the time of color changes and for capability of handling a larger number of colors.
A rotary atomizing head type coating system, which is arranged to reduce the amounts of discarding paint and solvent and to cope with an increased number of paint colors, has been known, for example, from Japanese Laid-Open Patent Publication No. H8-229446. The rotary atomizing head type coating system which is described in this Laid-Open Patent Publication employs paint cartridges which are filled with various paint colors and arranged to be replaceably mounted on the system in the course of a coating operation on vehicle body.
The just-mentioned prior art rotary atomizing head type coating system is constituted by a housing having a coating machine mount portion on the front side and a cartridge mount portion on the rear side thereof, and a coating machine being mounted on the coating machine mount portion of the housing and including an air motor with a rotational shaft and a rotary atomizing head located on the front side of the air motor and mounted on the rotational shaft of the air motor. Further, formed axially through the rotational shaft of the air motor on the coating machine is a feed tube passage hole which is opened at its fore end into the rotary atomizing head and at its rear end into the cartridge mount portion of the housing.
Further, the coating system is provided with a number of paint cartridges of different colors to be replaceably mounted on the cartridge mount portion of the housing. Each one of the paint cartridges is constituted by a container which is filled with paint, and a feed tube which is extended axially forward from a front end of the container. The container portion of the paint cartridge is adapted to be removably fitted in the cartridge mount portion of the housing, and the feed tube is inserted into the above-mentioned feed tube passage hole.
Further, by a movable partition wall, the container of each paint cartridge is divided into a paint chamber which is in communication with the above-mentioned feed tube, and an paint-extruding air chamber which is in communication with an extruding air supply passage which is provided on the side of the cartridge to supply extruding air to the paint-extruding air chamber. Furthermore, provided on the side of the housing are an extruding air passage to be brought into communication with the extruding air passage on the side of the cartridge. Therefore, as extruding air is supplied to the air chamber within the cartridge container through the extruding air passage on the side of the housing and the extruding air passage on the side of the paint cartridge, the movable partition wall is displaced in a forward direction, thereby pushing the paint in the paint chamber into the rotary atomizing head through the feed tube.
In the case of the rotary atomizing head type coating system which is arranged as described above, firstly a paint cartridge of a specific color is selected from a number of paint cartridges of various colors and mounted on the cartridge mount portion of the housing. Nextly, a certain amount of air is supplied to the extruding air chamber of the paint cartridge to spurt paint in the paint chamber of the cartridge toward the rotary atomizing head through the feed tube. As a result, the paint is sprayed toward an object to be coated from the rotary atomizing head.
At the time of changing the paint color, the paint cartridge on the coating machine is simply replaced by a fresh one. Namely, the paint color can be changed without wastefully discarding paint and solvent.
On the other hand, upon finishing a coating operation, the paint cartridge, which has been consumed by the coating operation, needs to be replenished after unloading same from the housing.
Therefore, a paint replenisher is used for refilling paint into the paint cartridge in the manner as follows. According to the above-mentioned prior art, a paint cartridge replenisher is constituted by a number of quick joints which are extended from paint circulating pipe systems which are allotted to the respective paint colors. When replenishing paint into the paint chamber of a cartridge by the use of this paint replenisher, a consumed paint cartridge is removed from the housing and returned to a stand. In the next place, a quick joint is connected to a paint refilling port which is provided on the cartridge separately from the above-mentioned feed tube, and paint is replenished into the paint cartridge.
That is to say, in the case of the paint cartridge replenisher according to the above-mentioned prior art, for the purpose of paint replenishment, a paint refilling port is provided on the side of the paint cartridge separately from the feed tube. This makes the construction of the paint cartridge more complicate and invites increases in production cost. In addition, there arises a problem that the paint cartridge has an increased number of points of possible paint leaks.
Further, as mentioned above, at the time of paint replenishment, a quick joint which is extended out from a paint circulating piping system is connected to the paint refilling port on the paint cartridge. Namely, due to the manual efforts which are required for connecting a quick joint to a paint refilling port on the side of a paint cartridge, the replenishment of paint cartridges has been objectionably time-consuming.
Furthermore, until next use, each used paint cartridge is put in a predetermined position at a waiting station, with the paint chamber of the cartridge container either in a replenished state or in a consumed state containing a certain amount of residual paint. Therefore, if the paint cartridge is left in the waiting state continuously, separation and sedimentation could occur to the pigment components of the paint in the cartridge. Especially in the case of pigments such as fragments of aluminum and mica, separation and sedimentation could occur within a short period of time.
As a consequence, non-uniform dispersal of pigments occur to the paint in the paint chamber of the cartridge, which may result in irregular color shadings as well as in degradations in quality of coated surfaces. In addition, separated sedimentary pigments may cause clogging and dysfunction of the feed tube or other paint passages.
In view of the above-discussed problems with the prior art, it is an object of the present invention to provide a method and an apparatus for replenishing paint into a paint cartridge, which can make paint cartridge construction simpler and permit to replenish paint cartridges in a facilitated manner.
It is another object of the present invention to provide a method and an apparatus for replenishing paint into a paint cartridge, which can prevent separation and sedimentation of pigments in paint to guarantee improved quality of coatings.
According to the present invention, for achieving the above-mentioned objectives, there is provided a method for replenishing paint into a paint cartridge which is divided into a paint chamber and an extruding liquid chamber by a movable partition wall, the method comprising the step of: putting paint in the paint chamber of the cartridge in respiratory circulation to and from a paint supply source by imparting repeated respiratory paint suck-in and push-out motions to the movable partition wall in case the paint cartridge is going to be retained in a waiting state for a long period of time until a next coating operation.
With the arrangements just described, in case a replenished paint cartridge is retained in a waiting state for a long period of time until a next coating operation, paint in a paint chamber of the cartridge is put in respiratory circulation to and from a paint supply source by repeated paint suck-in and push-out motions of a movable partition wall in the cartridge, thereby preventing separation and sedimentation of pigment components of the paint.
According to the present invention, there is also provided an apparatus for replenishing paint into a paint cartridge having a container and a feed tube extended axially forward form the container, the container being divided by a movable partition wall into a paint chamber in communication with the feed tube and an extruding liquid chamber to and from which an extruding liquid is charged and discharged, the apparatus comprising: a connector member adapted to connect a fore end portion of the feed tube to a paint supply source; and a respiratory paint circulation means connected to the extruding liquid chamber of the container, and adapted to arouse respiratory paint circulation between the paint chamber and the paint supply source by feeding the extruding liquid to and from the extruding liquid chamber, putting said movable partition wall in respiratory paint suck-in and push-out motions.
With the arrangements just described, upon finishing a coating operation, a fore end portion of a feed tube of a cartridge is connected to a paint supply source through the connector member in the replenishing stool, and an extruding liquid in an extruding liquid chamber of the cartridge discharged by the respiratory paint circulation means while sucking replenishing paint into a paint chamber of the cartridge from the paint supply source through the connector member and a fore distal end of the feed tube.
After replenishing paint in this manner and in case the replenished paint cartridge is to be retained in a waiting state for a long period of time until a next coating operation, an extruding liquid is fed to the extruding liquid chamber of the cartridge by the respiratory paint circulation means to push out paint in the paint chamber toward the paint supply source. Then, the extruding liquid in the extruding liquid chamber is discharged by the respiratory paint circulation means to suck paint into the paint chamber of the cartridge.
Accordingly, while in a waiting state, the respiratory paint circulation means can repeat a paint suck-in action of taking paint into the paint chamber of the cartridge from the paint supply source, alternately with a paint push-out action of pushing out paint in the paint chamber of the cartridge toward the paint supply source.
Further, according to the present invention, there is provided an apparatus for replenishing paint into a paint cartridge having a container and a feed tube extended axially forward form the container, the container being divided by a movable partition wall into a paint chamber in communication with the feed tube and an extruding liquid chamber to and from which an extruding liquid is charged and discharged, the apparatus comprising: a replenishing stool having a feed tube passage hole axially extended therethrough to receive the feed tube of the paint cartridge and having a container support portion formed on an upper open side thereof to support the container of the paint cartridge; a connector member provided within the replenishing stool at a deeper position than the feed tube passage hole and adapted to be connect a fore end portion of the feed tube to a paint passage leading to a paint supply source; a replenishing valve connected to the connector member through the paint passage to turn the paint passage into and out of communication; an extruding liquid feed passage provided in the replenishing stool and adapted to be connected to the extruding liquid chamber when the paint cartridge is set on the container support portion of the replenishing stool; and a respiratory paint circulation means connected to the extruding liquid feed passage, and adapted to arouse respiratory paint circulation between the paint chamber and the paint supply source by feeding the extruding liquid to and from the extruding liquid chamber while the paint passage is turned into communication through the replenishing valve, imparting respiratory paint suck-in and push-out motions to the movable partition wall.
With the arrangements just described, a paint cartridge is set on the container support portion which is formed on the replenishing stool of the paint replenisher, with a feed tube of the cartridge passed into the feed tube passage hole until its fore end is engaged with the connector member. In this state, an extruding liquid in an extruding liquid chamber of the cartridge is discharged by the respiratory paint circulation means to suck paint into a paint chamber of the cartridge.
In case the replenished paint cartridge is retained in a waiting state for a long period of time until a next coating operation, the extruding liquid is fed to the extruding liquid chamber of the cartridge by the respiratory paint circulation means to push out paint in the paint chamber toward the paint supply source. Then, the extruding liquid in the extruding liquid chamber of the cartridge is discharged by the respiratory paint circulation means to suck paint into the paint chamber of the cartridge.
Accordingly, while in a waiting state, paint is constantly circulated between the paint chamber of the cartridge and the paint supply source by respiratory actions of the respiratory paint feed circulation means.
The connector member according to the present invention is preferably axially movably provided within the replenishing stool and constantly urged toward the feed tube by a spring interposed between the connector member and the replenishing stool.
With the arrangements just described, as a paint cartridge is set on the replenishing stool, a fore end portion of the feed tube fitted into the connector member. At this time, the connector member is moved axially to a certain extent depending upon an axial position of the fore end portion of the feed tube. Besides, by the spring, the connector member is pushed against the feed tube and securely held in liquid-tight fitting engagement with the feed tube.
Further, according to the present invention, the replenishing valve is preferably constituted by a paint inlet port connected to the paint supply source, a paint outlet port for connecting the paint inlet port to the connector member, a wash liquid supply port for connecting the paint outlet port to a wash liquid supply source, a wash liquid discharge port for connecting the paint outlet port to a drain side, a paint feed valve for opening and closing the paint inlet port, a wash liquid supply valve for opening and closing the wash liquid supply port, and a wash liquid discharge valve for opening and closing the wash liquid discharge port.
With the arrangements just described, when the paint supply port is closed by the paint feed valve and the wash liquid supply port is opened into communication by the wash liquid supply valve, the connector member is connected to the wash liquid supply source through the wash liquid supply valve. Therefore, as the extruding liquid in the extruding liquid chamber of the cartridge is discharged by the respiratory paint circulation means, a wash liquid is sucked into the paint chamber of the cartridge from the wash liquid supply source.
On the other hand, when the wash liquid supply source is closed by the wash liquid supply valve and the wash liquid discharge port is opened into communication by the wash liquid discharge valve, the connector member is communicated with the drain side through the wash liquid discharge valve. Therefore, as the extruding liquid is fed to the extruding liquid chamber of the cartridge by the respiratory paint circulation means, washing liquid in the paint chamber of the cartridge is pushed out toward the washing liquid supply source.
The paint chamber and feed tube of the paint cartridge are washed clean as the wash liquid is repeatedly sucked and pushed out to and from the paint chamber in the manner as described above.
Further, according to the present invention, the respiratory paint circulation valve is preferably constituted by an extruding liquid supply port connected to the extruding liquid source, an extruding liquid discharge port connected to an extruding liquid reservoir tank, a respiratory extruding liquid port connected to the extruding liquid feed passage, and a directional control valve for connecting the respiratory extruding liquid port to the extruding liquid supply port or discharge port.
With the arrangements just described, at the time of replenishing paint into the paint chamber of a cartridge, the directional control valve is switched to communicate the extruding liquid feed passage with the extruding liquid discharge port. Whereupon, the extruding liquid chamber of the cartridge is connected to the extruding liquid reservoir tank. Therefore, as the extruding liquid is discharged from the extruding liquid chamber of the cartridge, paint is sucked into the paint chamber under the influence of the paint supply pressure of the paint supply source.
On the contrary, when the directional control valve is switched to communicate the extruding liquid feed passage with the extruding liquid supply port, the extruding liquid chamber of the cartridge is connected to the extruding liquid supply source. Therefore, in this case the extruding liquid is supplied to the extruding liquid chamber of the cartridge, thereby pushing out paint in the paint chamber of the cartridge toward the paint supply source.
Further, preferably the above-mentioned connector member is provided with a feed tube positioning means for guiding a fore end portion of the feed tube into position when engaged therewith.
With the arrangement just described, upon fitting a fore end portion of the feed tube into the connector member, the fore end of the feed tube is automatically oriented into a fixed position within the connector member by the feed tube positioning means.
Further, according to the present invention, the container support portion of the replenishing stool is provided with a container positioning portion adapted to guide the container of the cartridge into position by engagement with a front portion of the container.
With the arrangement just described, upon setting a paint cartridge on the container support portion of the replenishing stool, a front portion of the cartridge container is engaged with the containing position portion and thereby oriented into a fixed position on the container support portion.
Further, according to the present invention, the paint replenisher further comprises a vacuum space to be defined between the container support portion of the replenishing stool and the paint cartridge when the paint cartridge is set on the container support portion, an air suction passage provided in the replenishing stool and opened to the vacuum space, air in the vacuum space being sucked through the air suction passage to hold the paint cartridge fixedly on the container support portion by suction force.
With the arrangements just described, after fitting a container of a paint cartridge in the container support portion of the replenishing stool, air is sucked out through the air suction passage to evacuate the vacuum space which is defined between the container support portion and the cartridge container, so that the paint cartridge is retained fixedly in the container support portion of the replenishing stool by suction grip. On the other hand, at the time of removing the paint cartridge from the replenishing stool, air is supplied to the vacuum space to free the paint cartridge from the suction grip.
Further, according to the present invention, the paint replenisher further comprises a pilot air passage provided in the replenishing stool to supply pilot air to a paint valve provided on the side of the paint cartridge.
With the arrangement just described, pilot air is supplied through the pilot air passage at the time of replenishing paint into a paint cartridge to open the paint valve in the cartridge. Accordingly, paint can be replenished into the cartridge through the passage within the feed tube. Upon finishing a paint replenishing operation, the supply of pilot air is cut off to close the paint valve, thereby preventing paint leaks through the feed tube of the cartridge.